The past days I noticed an oil leakage just above the exhaust manifold, that leakage caused some smoke coming from the manifold. At first I thought the gasket around the rocker cover was the culprit, then I suspected the small gasket rings around the rocker cover bolts but none of there would some the oil leakage. Then I took off the rocker cover and cleaned it thoroughly. I noticed two (!) cracks:

I used some liquid gasket seal as a temporary fix as these cracks meant I had to find a new rocker cover… And that takes some time as the plastic m52 sing-Vanos covers are hard to find as second hand (in Holland).